Microbiologically influenced corrosion of biodegradable Zn-Mn alloys by Lactobacillus acidophilus

Abstract

Zinc-based alloys are promising biodegradable materials for application in the intestinal environment due to their appropriate degradation rates and favorable biocompatibility. However, the corrosion and degradation of biodegradable zinc alloys in the presence of intestinal microorganisms are seldom investigated. In this study, binary Zn-Mn alloys with 0.4 and 0.8 wt.% Mn content were fabricated using the extrusion process. The corrosion behaviors of pure zinc and Zn-Mn alloys with the existence of Lactobacillus acidophilus, a representative microorganism in the intestinal tract, were systematically investigated. In comparison to pure zinc, both Zn-Mn alloys exhibited enhanced strength and ductility. L. acidophilus significantly accelerated the corrosion of both pure zinc and Zn-Mn alloys by generating acidic agents. The presence of L. acidophilus increased the i_corr values for pure zinc, Zn-0.4Mn, and Zn-0.8Mn from 68.7 ± 9.9, 33.9 ± 2.3 and 17.1 ± 0.1 μA cm⁻² to 253.5 ± 26.7, 167.6 ± 8.7 and 30.6 ± 2.2 μA cm⁻², respectively. The addition of Mn mitigated corrosion by refining grains and reducing the local surface potential difference. Compared to pure zinc, the surface potential difference of Zn-0.8Mn decreased from 31.8 ± 1.7 mV to 11.8 ± 0.9 mV. This study points out the existence of microbiologically influenced corrosion in the intestinal environment and emphasizes its importance in the comprehensive design of biodegradable zinc alloys.